MathDB
Hard geometry

Source: Komal,Jan 2015

May 16, 2015
geometryincenter

Problem Statement

Let ABCDABCD be a convex quadrilateral. In the triangle ABCABC let II and JJ be the incenter and the excenter opposite to vertex AA, respectively. In the triangle ACDACD let KK and LL be the incenter and the excenter opposite to vertex AA, respectively. Show that the lines ILIL and JKJK, and the bisector of the angle BCDBCD are concurrent.